Fixed Windows build.

src/Battling/Flow/ChoiceQueue.cpp

@@ -2,7 +2,7 @@
 
 bool CreatureLib::Battling::ChoiceQueue::MoveCreatureChoiceNext(CreatureLib::Battling::Creature* creature) {
     // Find which index the creature choice is at.
-    size_t choiceIndex = -1;
+    size_t choiceIndex = SIZE_MAX;
     for (size_t index = _current; index < _queue.size(); index++) {
         if (_queue.at(index)->GetUser() == creature) {
             // If the creature choice is already next up, return.
@@ -12,7 +12,7 @@ bool CreatureLib::Battling::ChoiceQueue::MoveCreatureChoiceNext(CreatureLib::Bat
         }
     }
     // If the creature has no choice anymore, return.
-    if (choiceIndex == -1)
+    if (choiceIndex == SIZE_MAX)
         return false;
 
     // Save the pointer to the creature choice.